Here's the latest discussion from the NWS:
Area Forecast Discussion National Weather Service Indianapolis IN 917 AM EST Fri Jan 17 2020 .UPDATE... The NEAR TERM and AVIATION Sections have been updated below. && .SYNOPSIS... Issued at 320 AM EST Fri Jan 17 2020 High pressure overhead will steadily move east of the region, as a strengthening area of low pressure lifts northeast from the Southern Plains reaching Southern Wisconsin saturday morning. This low pressure system will then quickly lift northeast with a frontal boundary pushing east across Central Indiana, allowing another surface ridge of high pressure to approach the Western Ohio River Valley late in the weekend with much cooler temperatures. && .NEAR TERM /Rest of Today/... Issued at 912 AM EST Fri Jan 17 2020 Forecast is evolving as expected. Current thoughts remain that precipitation will begin late this afternoon as mix of rain and snow with brief periods of freezing rain tonight before all rain by late tonight and tomorrow. No changes made to snow and ice accumulations. Previous discussion follows... Early this morning a steady feed of dry northeast flow has kept clouds out of the area, but temperatures have radiated into the upper teens to lower 20s with dewpoints several degrees lower due to the drying in the lower levels of the atmosphere. Given the expected progressive flow, the anticipation is that the departing surface ridge will loosens it`s influence on Central Indiana, and likely allow steady moistening in the lower levels late this afternoon/evening ahead of the next system. That being said, there is some indications that the further downstream ridge may be slightly delayed from pushing east, and thus allow some subsidence to linger into the evening and perhaps delay the onset of precip by a few hours. This could be key in lowering snowfall totals, which presently is around an inch for the northern counties. Any delay in precip may also impact the potential for freezing rain to occur as well. Forecast soundings continue to indicate a warm layer aloft lifting overhead after 6pm this evening, setting the stage for a slow but steady transition from the moist dendrites towards a full melt of falling dendrites towards freezing rain due to a sub-freezing surface. Guidance has backed off marginally with ice accums, with less than one tenth for the overnight hours. Have adjusted the current headline to include two row of counties further south, but expect the timing to be a short period and by 9z Sat any precip that will be falling will likely be just rain. Further north soundings still support some sub-freezing conditions, but expect this to be transitioning to all rain by daybreak Sat and will maintain the ending of the headlines at 12Z sat further north. Temperatures will be slowly rising overnight, so the low temps will occur prior to midnight in the upper 20s to around 30 range, pushing into the lower to middle 30s by 9-12z Sat. && .SHORT TERM /Saturday through Sunday night/... Issued at 320 AM EST Fri Jan 17 2020 Warm/Moist conveyor will be ushering in a mild slug of air Sat with temps quickly pushing into the 40s to perhaps lower 50s in the southern forecast area. Otherwise the main concern will be on the QPF totals given the remaining saturated soils across Central Indiana. Expect steady rain to arrive shortly after daybreak and linger through late morning, coupled with moderate forcing, and precip totals could easily be between .5 to .75 inches before noon. A dry wedge is progged to quickly lift northeast as the mid-level trough axis arrives between 15-18Z Sat, which should bring a brief end to the precip. But with cold air advection then kicking in and wrap-around moisture bringing precip chances quickly back to the region by early afternoon and transitioning any precip to all snow. Given the northwest flow and cold air advection behind the frontal passage, the depth of the moisture is not substantial. Thus not anticipating much in the way of accumulations on the back end of the shortwave Sat afternoon. But temperatures will be falling through the afternoon into the 30s. Quick push towards more typical winter like pattern for Sat ngt into Sun, with a potent thermal trough arriving and allowing temps Sat ngt to radiate into the single digits to lower teens. Northwest cold air advection will persist, but expected to be dry given strong subsidence from a surface ridge displaced to the northwest of the region. Broad mid-level trough will then arrive over the Great Lakes/Ohio River Valley regions, holding Sun high temps in the teens to lower 20s. There is some indications of a weak clipper like system traversing the region later in the day Sun/early Mon, but this looks to remain further north. && .LONG TERM /Monday through Friday/... Issued at 358 AM EST Fri Jan 17 2020 For the majority of the extended period, conditions will be quiet as high pressure builds over the Great Lakes region. A shortwave or two embedded within an elongated trough to the north may progress towards Indiana in the expected northwest flow Monday and Tuesday. However, a lack of moisture will limit the possibility of precipitation. For now, no precipitation has been included in Days 4 through 6, but future updates may include a slight chance. High pressure and consistent northerly flow should allow for temperatures to remain below normal Monday and Tuesday. Warmer temperatures are expected to return Wednesday through the extended as high pressure moves over the east coast, and southwesterly flow dominates the region. The next opportunity for precipitation will be Friday. A significant storm system is expected to develop downstream of a amplified upper- level trough late next week. Models are rather inconsistent with the timing and location of this storm system. For now, warmer temperatures looks likely for Friday, with a chance of perception from the aforementioned system. &&
Will it ever snow???
ReplyDeleteFebruary looks like our last chance. #BOTS!
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